A soldier thought to have killed himself after murdering student Sally Geeson had been sent to a military jail for holding a woman captive.
Miss Geeson's body was found in woodland at a cemetery
L/Cpl David Atkinson, 31, is thought to have murdered Miss Geeson, 22, after she vanished on New Year's Day.
The Army said he was cleared of kidnap and assault in 1998 but served eight months in prison after falsely imprisoning an 18-year-old in Germany.
Miss Geeson's mother described the information as "very disturbing".
In February 1998, Atkinson, of East Kilbride, Lanarkshire, was fined £1,000 after being found guilty of falsely imprisoning the Polish woman while he was stationed in Germany.
It was unclear on Monday night how he had imprisoned the woman.
He had already served eight months in a military prison after he was arrested in connection with the incident, said a Ministry of Defence spokesman.
Officials said L/Cpl who was based at the Royal Engineers' Waterbeach barracks near Cambridge, rejoined his unit after the court martial.
Miss Geeson's mother, Sue, said: "We weren't aware of this. It's certainly concerning. Questions will have to be asked as to why he was still in the Army - especially at a barracks so near to a town like Cambridge. It's very disturbing."
L/Cpl Atkinson's body was found outside a hotel in Glasgow about 12 hours after Miss Geeson's body was found in woodland at Madingley, near Cambridge.
He is believed to have committed suicide by jumping from the seventh floor of the Corus Hotel in the early hours of Saturday morning after setting himself on fire.
Sally Geeson's disappearance
1 Jan: Sally Geeson last seen leaving a New Year's Eve party in Cambridge
3 Jan: Cambs Police make appeal for information
7 Jan: A body is found at Madingley, near Cambridge
8 Jan: The body is identified as Miss Geeson
9 Jan: Police say that a man found dead in Scotland was a suspect in the case
10 Jan: Police carry out forensic tests on the man
Miss Geeson, from Southend, Essex, a forensic science student at Anglia Polytechnic University in Cambridge, disappeared after celebrating the start of 2005 in a Cambridge pub.
Her naked body was found about three miles away on Friday.
The Royal Military Police knew L/Cpl Atkinson was in Cambridge on the night of 31 December and that he had been due to report for duty on 4 January.
He failed to do so, and Cambridgeshire Police were alerted by the Royal Military Police.
The murder inquiry team confirmed scientists were attempting to establish if Miss Geeson had been sexually assaulted before her death.
Ms Geeson had been due to start her final exams at Anglia Polytechnic University this week.